The Essay: John Boyne argues that great books can break through every barrier of age

A confession: when I completed The Boy in the Striped Pyjamas in 2005, it was the closest I had come to a children's book since 1982 when, aged 11, I decided never to go upstairs in my local library again. Upstairs, after all, was for kids. Downstairs was where the grown-up books were stocked; that was where the real action was: novels about cheating French wives, schoolboys taking a trip to Manhattan for the day, a series of Rabbit novels that had nothing to do with Watership Down.

These books I had heard about and, in my precocious desire to immerse myself in literature, wanted desperately to read. The first book I checked out, blushing furiously as I handed it across to an amused looking librarian, was Anna Karenina. Later that day, already holding strong opinions on whether or not Dolly should take Stiva back, I pulled all the children's books off the shelves in my bedroom and threw them in a box under my bed. The empty wall space was ready for the next stage of my reading.

Almost a quarter century later when my fifth novel, but first children's book, was about to be published, I had an urge to reacquaint myself with some of those books I had loved as a boy and went looking for that box. I wasn't surprised to find it. My mother, after all, would never throw a book away.

Opening that box was like rediscovering my childhood. Each book held a special memory for me. The summer in Wexford when I had devoured Secret Seven adventures: the Seven, who could be quite bitchy towards each other, forever throwing someone out of their club for saying the wrong thing, were a much more entertaining read for me than the rather smug Famous Five. The school trip to Bath when I had boarded a raft down the Mississippi with Huckleberry Finn while sailing with my classmates from Dun Laoghaire to Holyhead. The week I had spent in hospital after an appendectomy and my mother bought me a copy of The Magician's Nephew, the first of CS Lewis's Narnia tales, the seventh of which I had devoured by the time the stitches came out.

Those books! Those classics of children's literature. Why had I discarded them so easily, I wondered. They needed to be rescued: returned to their proper places, dusted off, spines out. But first, I had to read them again.

I didn't read them all, of course. But I waved to the passengers alongside The Railway Children as the trains passed through Three Chimneys. I camped out with the Walker children of Swallows and Amazons and joined Emil and his gang of young detectives as they hunted down the thief. And with every book I read, I grew more admiring of these wonderful works and excited that I was about to publish a novel that would I hoped bring my work to a young audience for the first time.

What makes a classic is difficult to define. It's entirely subjective, of course. And the term is employed far too promiscuously. Last year, I read 96 novels in total, eight of which were written for children or young adults, and looking at the list now – yes, I keep a list of books I read; so sue me – there's only one title that I think will be considered a classic in 50 years' time. I read some good books, of course; some very good books. But only one that I think combines arresting language with a central character whose struggle becomes the reader's struggle, an honest, heart-wrenching story that moved me to tears. And that one book just happens to be one of the children's books: A Monster Calls by Patrick Ness.

The phrase "children's classic" contains twice as many words as necessary. It's either a classic or it's not; whether it's written for children is neither here nor there. Indeed, looking at the list of titles published in the new Vintage Children's Classics list, there are some books which have, over time, become defined as children's books when really they're just books, no prefix required. Anna Sewell's Black Beauty, for example; the two Mark Twain novels; Dickens's A Christmas Carol; Kipling's The Jungle Book.

These are books that can be read and enjoyed by readers of all ages. I had started typing the phrase "as opposed to", thinking that I would mention some of the books on the list which really could only be enjoyed by children, but looking at the titles I couldn't find any. Perhaps that's exactly what makes these books classics. They feature young heroes and heroines, from Heidi to Cassandra Mortmain of Dodie Smith's I Capture The Castle, from Alice to Peter Pan, whose adventures or struggles are equally engaging to anyone who believes that the human experience is best defined and understood through the art of fiction, the power of storytelling, regardless of whether the hands holding the book belong to a child or a centenarian.

The book that stands out for me as a great children's classic, one that fascinated and terrified me as a boy and which retained all its power when I returned to it as an adult, is Ian Seraillier's The Silver Sword. The novel was my first introduction to the Second World War in fiction, to the horrors of the Nazi era and the fear that capture could instill in the minds of its young heroes Ruth, Edek and Bronia. The novel opens with an escape as Joseph Balicki, a Polish schoolteacher who has been taken to a concentration camp for turning pictures of Hitler to the wall, renders a guard unconscious, steals his uniform and makes his way back to Warsaw in search of his wife and children, only to find the city is a shell and his family have disappeared. The story of what has happened is gradually revealed.

It's a marriage of great storytelling with characters that display the kind of bravery and resilience that the best heroes of children's literature do. I owe Seraillier a debt; his novel engendered in me a fascination with the Second World War and the Holocaust that ultimately led me to write The Boy in the Striped Pyjamas, a novel published 50 years after Seraillier's masterpiece.

I hope for so much from every book I read. And time and again, I find myself disappointed. I look across my bookshelves and see hundreds of titles which in my memory seem merely mediocre or second-rate. Only occasionally does a novel appear for which I feel a lasting passion, a book that I think could in time become a classic. As this new collection of children's classics is published, it's interesting to consider the modern titles that, 50 years hence, will have earned their place. Of course, Mark Haddon's The Curious Incident of the Dog in the Night-Time, a great novel, complex and intelligent, is already there. I could make a strong case for Malorie Blackman's Noughts and Crosses series, for Flour Babies by Anne Fine, for Philip Ardagh's Eddie Dickens trilogy, for Roddy's Doyle's Wilderness. Philip Pullman, Michael Morpurgo, Jacqueline Wilson? Yes, of course. And any serious reader who has not read the late Siobhan Dowd is missing out on novels as powerful and moving as any published over the last decade.

Sadly, there remains an unwillingness among adults to engage with literature written for young people unless it has been made into a repetitive series of film adaptations or defined by the trade by that most reductive of terms, the "crossover" novel. When aspiring writers tell me they are writing a crossover novel it makes me want to bang my head – or theirs – against a wall. Do they think that Robert Louis Stevenson got to the end of Treasure Island and turned to his wife Fanny to say that he had completed a crossover novel?

And of course there was that ill-considered remark from Martin Amis a few years ago that only a serious brain injury could make him want to write for young readers: an extraordinary statement from someone who clearly worships good writing as much as Amis does. But as long as writers of children's literature are willing to engage with serious subjects in a fearless way, taking their readers on emotional journeys that remain with them throughout their lives, then work will continue to be produced that proves worthy of the term "classic". In which case, more readers might be willing to venture upstairs in the library once again. The seats are more comfortable up there anyway; I've never passed a bean-bag I didn't want to sit in.

John Boyne's 'The Boy in the Striped Pyjamas' is one of 20 books on the inaugural Vintage Children's Classics list. His 'The Terrible Thing That Happened To Barnaby Brocket' is published this month by Doubleday